This invention relates generally to electronic devices and in particular to test and measurement instruments for detection and measuring the strength of an electromagnetic field.
There are many situations and applications where it is desirable to detect, locate and measure electromagnetic emission at some distance from the emitting object. For example, in the case of high voltage power equipment and cables, high frequency electromagnetic emission from a motor or a generator is an indication of an internal problem in the motor or the generator, such as when the internal insulation in the motor or generator is beginning to break down. It is desirable to be able to detect this high frequency emission, but it is unsafe for a human to approach the high-voltage lines. Current methods for identifying the presence of high-frequency emissions involves carrying bulky normally stationary equipment, such as spectrum analyzer, to the site where the identification is being conducted. Even with this conventional spectrum analyzer, it is impossible to determine from which particular cable or piece of equipment the electromagnetic field is emanating. In addition, the quantitative analysis of the emitted power is very difficult to perform using conventional equipment because the conventional receiving antennae receive signals from a variety of different emission sources rather than just from the emission source in question. Therefore, there is no practical way, with these conventional systems, to estimate the emitting power of the emission source. It is desirable, however, to be able to accurately measure the emitting power of the emission source.
Another example of a situation where it is desirable to detect, locate and measure electromagnetic emission at some distance from the source is wireless area networks, where so-called access points (i.e., radio network nodes) are situated high on the ceiling, etc.. It is advantageous and desirable to be able to verify proper radio operation of the particular access point from the ground without the need to climb up a ladder. Conventional systems and devices for troubleshooting and diagnosing problems of such access points allow neither for diagnostics to be run for a particular access point nor for determining the output power of the access point.
It is also important to be able to measure emission parameters in the presence of interfering signals. Current systems which offer some means of restricting measurements to a specific direction of emission are bulky and therefore cannot be made truly portable.
Thus, none of the conventional systems permit electromagnetic radiation to be detected, accurately located and measured at some distance from the emission source. In addition, none of the conventional systems or devices may be embodied in an inexpensive, hand-held device. Therefore, it is desirable to provide an apparatus for detecting, locating and measuring electromagnetic radiation which solves the problems of conventional systems and devices and it is to this end that the invention is directed.